1. FIELD OF THE INVENTION
The present invention relates to a circuit breaker operating on leakage occurrence, and more particularly to a circuit breaker suitable for a synchronous generator using semiconductor voltage control system.
2. DESCRIPTION OF THE PRIOR ART
Generally, a circuit breaker operating on leakage occurrence (hereinafter, which is called as a leakage operating breaker) is necessarily provided in the generator or the associated lead circuit for purpose of preventing an electric shock and fire when leakage, for example, due to poor insulation, occurs in the synchronous generator circuit.
A conventional leakage operating breaker is constructed such that the leakage current detected by the coil is applied through the semiconductor amplifier to a mechanically constructed relay for quick circuit interruption, which is generally rated at 15 mA in interruption current and less than 0.1 sec. in tripping, and is used in connection with breakers.
The conventional leakage operating breaker is complicated due to its associated amplifier and quick circuit interruption device, resulting in a high manufacturing cost, and becomes large in size, two or three times, for example, the conventional one. The fact that a mechanical switch which is not so frequently operated is used results in poor reliability. This partly prevents the use of such a leakage operating breaker. With the recent trend of safety requirements for the electric appliance, however, the need of the leakage operating breaker of such type increases and thus an economic and compact leakage operating breaker is highly desired.